The 19-year-old Dubliner came on with a quarter hour remaining at St. Andrews and certainly caught the eye as Rovers drew 1-1 with Birmingham City.
Speaking after the match Bowyer was happy to give the Irish Under-21 international his first outing in a Rovers shirt.
"I was delighted to get John O'Sullivan on for his debut," said Bowyer.
"I'm delighted for John, he's had to work hard and it sends him into the summer knowing that he has to continue to work hard.
"It gives him something to strive for over the close season.
"If he wants to be a professional footballer then he has had a taste of it. That was the plan to give him a taste of it.
"He needs to look after himself now and work very very hard in the summer."